Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$96.60	10.669%	$106.9063	$106.91	$106.90	$106.90
Purchase #2	$29.31	13.129%	$33.1581	$33.16	$33.15	$33.20
Purchase #3	$73.48	11.831%	$82.1734	$82.17	$82.15	$82.20
Purchase #4	$178.86	10.461%	$197.5705	$197.57	$197.55	$197.60
Purchase #5	$236.28	7.131%	$253.1291	$253.13	$253.15	$253.10
Purchase #6	$185.80	13.162%	$210.255	$210.26	$210.25	$210.30
Purchase #7	$229.61	13.811%	$261.3214	$261.32	$261.30	$261.30
7 purchase totals =	$1,029.94		$1,144.5138	$1,144.52	$1,144.45	$1,144.60